1. Field of the Invention
The present invention pertains to the storage of information, and particularly to automated cartridge handling systems such as cartridge libraries which store cartridges or cassettes of magnetic tape.
2. Related Art and Other Considerations
The economic and compact storage of information is increasingly important in the computer industry, particularly so as the computer unleashes new potentials in numerous fields such as audio visual and/or multimedia.
In the early days of computers, information requiring storage could be transmitted from a computer to a tape drive, whereat the information was magnetically recorded on or read from a large reel of tape. Upon completion of an operation of recording on the tape, for example, the reel would be removed manually from the tape drive and mounted in a rack. Another reel from the rack could then be manually mounted, if necessary, in the drive for either an input (tape reading) or output (recording to tape) operation.
Eventually it became popular to enclose magnetic tape in a cartridge, the cartridge being considerably smaller than the traditional tape reels. While many persons are familiar with tape cartridges of a type which can be loaded into a "tape deck" for reproduction of audio information (e.g. music), it is not as commonly realized that similar cartridges, although of differing sizes, can be used to store such information as computer data. For years now magnetic tape cartridges have proven to be an efficient and effective medium for data storage, including but not limited to computer back-up.
Large computer systems have need to access numerous cartridges. To this end, automated cartridge handling systems or libraries for cartridges have been proposed for making the cartridges automatically available to the computer. Many of these automated libraries resemble juke boxes. Typically, prior art automated cartridge libraries have an array of storage positions for cartridges, one or more tape drives, and some type of automated changer or cartridge engagement/transport mechanism for picking or gripping a cartridge and moving the cartridge between a storage position and the tape drive.
The following United States patents, all commonly assigned herewith and incorporated herein by reference, disclose various configurations of automated cartridge libraries, as well as subcomponents thereof (including cartridge engagement/transport mechanisms and storage racks for housing cartridges):
U.S. Pat. No.4,984,106 to Herger et al., entitled "CARTRIDGE LIBRARY SYSTEM AND METHOD OF OPERATION THEREOF". PA1 U.S. Pat. No.4,972,277 to Sills et al., entitled "CARTRIDGE TRANSPORT ASSEMBLY AND METHOD OF OPERATION THEREOF". PA1 U.S. Pat. No.5,059,772 to Younglove, entitled "READING METHOD AND APPARATUS FOR CARTRIDGE LIBRARY". PA1 U.S. Pat. No.5,103,986 to Marlowe, entitled "CARTRIDGE RACK". PA1 U.S. Pat. Nos.5,237,467 and 5,416,653 to Marlowe, entitled "CARTRIDGE HANDLING APPARATUS AND METHOD WITH MOTION-RESPONSIVE EJECTION". PA1 U.S. Pat. No. 5,498,116 to Woodruff et al., entitled "ENTRY-EXIT PORT FOR CARTRIDGE LIBRARY". PA1 U.S. Pat. No. 5,487,579 to Woodruff et al., entitled PICKER MECHANISM FOR DATA CARTRIDGES". PA1 U.S. Pat. No. 5,718,339 to Woodruff et al., entitled "CARTRIDGE RACK AND LIBRARY FOR ENGAGING SAME".
Important to the automation of cartridge libraries as previously known has been the provision of the cartridge changer or cartridge engagement/transport mechanism for picking or gripping a cartridge and moving the cartridge between a storage position and the tape drive. Such rotobic mechanisms, often called a cartridge "picker" or "gripper", is typically mounted in a library frame in order to introduce and remove cartridges relative to one or more stationary drives. The stationary drive and the picker are mounted to the same basic frame structure of the library, but otherwise are structurally independent.
A cartridge library with a movable drive has been proposed in U.S. Pat. No. 5,739,978, entitled CARTRIDGE HANDLING SYSTEM WITH MOVING I/O DRIVE, which is incorporated herein by reference. In such arrangement, a tape drive moves (e.g., pivots) into alignment and then linearly moves into operative relation to receive the cartridge. This arrangement essentially obviates use of a cartridge "gripper" or "changer", since the drive itself performs that function.
In some drives it is necessary that a "soft" load be performed. That is, a cartridge must first be inserted partially into the drive slot, and thereafter an additional force provided in order to insert fully the cartridge into the drive. Traditionally, the additional force has been accomplished by backing the gripper away from the drive after the cartridge has been partially inserted into the slot, and then having the gripper return in a second motion to push the cartridge entirely into the drive.
What is need therefore, and an object of the present invention, is method and apparatus for effectively handling cartridges in a cartridge library.